(1) Field of the Invention
The invention is related to an actuating system for an actuatable door, said actuating system comprising the features of claim 1. The invention is further related to an actuatable door, in particular for an aircraft, said actuatable door having such an actuating system and comprising the features of claim 15.
(2) Description of Related Art
Actuatable doors and, in particular, actuatable cargo doors in aircrafts usually fulfill the following major functions: They close the aircrafts in operation for maintaining a required internal pressure therein, they contribute to carrying flight loads in corresponding lower deck cargo compartments and they allow external access to the corresponding lower deck cargo compartments. Therefore, robust and safe actuating systems are required for reliably and safely closing the actuatable doors in operation, but also for fulfilling all relevant requirements defined by the competent authorities, such as e.g. in EASA CS 25.783 related to fuselage doors in general.
More specifically, according to EASA CS 25.783d (2) such actuating systems require latching hooks and corresponding latching devices that must be designed so that, under all aircraft flight and ground loading conditions, there is no force or torque tending to unlock the latching hooks in closed state of the actuatable door. In addition, the latching devices must include means for securing the latching hooks in an associated locked state. These means must be independent of the latching devices.
Furthermore, according to EASA CS 25.783d (5), locking members such as locking cams must be provided for locking the latching hooks in the associated locked state. However, any positioning of the locking members in a locking position, wherein the locking members lock the latching hooks, must be prevented as long as the latching hooks and the corresponding latching devices are not in their associated locked state.
The document DE 198 25 405 C2 describes a conventional actuating system for an actuatable door that fulfills these requirements and comprises a plurality of latching devices, each being provided with an associated latching hook that is adapted for locking the actuatable door in a closed position. Each latching hook is securable in its locked state by means of a separate rotatable locking device, which is implemented as a locking cam.
More specifically, each latching hook is pivotally mounted to a first pivot bearing and connected to a pivotable mechanical transmission element via a coupling link. The latter is implemented as a first coupling rod and on the one hand pivotally mounted to the latching hook by means of a second pivot bearing and on the other hand to the pivotable mechanical transmission element by means of a third pivot bearing. The pivotable mechanical transmission element is implemented as a bell crank, which is pivotable around an associated bell crank bolt defining a fourth pivot bearing. The bell crank is further coupled to a latch lever by means of a coupling link, which is implemented as a second coupling rod. The latter is on the one hand pivotally mounted to the bell crank by means of a fifth pivot bearing and on the other hand to the latch lever by means of a sixth pivot bearing. The latch lever is coupled to a rotatable latching shaft, which defines a seventh bearing of the conventional actuating system.
The documents EP 0 222 160 A2, US 2003/146643 A1 and DE 199 44 615 A1 also describe conventional actuating systems. These conventional actuating systems are, however, similar to the one described in the document DE 198 25 405 C2 and are, therefore, not described in more detail for brevity and conciseness.
When operating the conventional actuating system according to the document DE 198 25 405 C2 for locking the actuatable door in the closed position, the rotatable latching shaft is rotated in a predetermined rotational direction, thereby rotating the latch lever also into this predetermined rotational direction until the latch lever and the second coupling rod are in-line. The rotating latch lever entrains the second coupling rod, which in turn entrains the bell crank, thereby pivoting the latter into an opposed rotational direction. The pivoting bell crank thereby pushes the first coupling rod such that the latter rotates the latching hook also into this opposed rotational direction until the latching hook reaches a locking position, wherein the actuatable door is locked in the closed position. Subsequently, the locking cam is rotated in a securing position for securing and blocking the latching hook in its locked state.
For further securing and blocking the latching hook in its locked state such that the latching hook cannot be rotated accidentally or involuntarily from its locking position back into a releasing position, wherein the actuatable door can be opened, the first coupling rod is driven by the pivoting bell crank into a so-called “overcentered” position. This is done by shortening or lengthening the second coupling rod.
More specifically, the overcentered position is defined such that any rotation of the latching hook in the above described predetermined rotational direction for unlocking the latching hook due to an external force acting on the latching hook, would only lead to a further rotation of the bell crank into the above described opposed rotational direction, which is prevented by means of the second coupling rod and the latch lever. In other words, when the first coupling rod is in the overcentered position, the latching hook can only be driven from its locking position into its releasing position by rotating the latch lever into the above described opposed rotational direction by means of the rotatable latching shaft.
However, the above described conventional actuating system is comparatively complicated and expensive, as each latching device thereof, i.e. without the separate rotatable locking device, comprises multiple constituent components including five moving parts in row with seven bearings involved, count starting with the rotatable latching shaft, adding up all individual tolerances of these constituent components. Consequently, this conventional actuating system is comparatively heavy and volume consuming and manufacturing and assembly thereof is rather complicated due to the great number of components and tolerances. Furthermore, every opening in the latching device of the conventional actuating system that is used to define one of the above described bearings leads in the vertical stress load path defined by the latching device to an increased material thickness of a corresponding component, as this is required for compensating weakening effects of the openings.
It is, therefore, an object of the present invention to provide a new actuating system for an actuatable door that comprises less constituent components, is easier to produce and assemble and comparatively inexpensive to manufacture. Furthermore, it is an object of the present invention to provide a new actuatable door comprising such a new actuating system.
This object is solved by an actuating system for an actuatable door, said actuating system comprising the features of claim 1.
More specifically, according to the present invention an actuating system for an actuatable door comprises an actuatable rotatable latching shaft and at least one latching device, the at least one latching device comprising a latching hook, an associated pivot bearing, a pivotable mechanical transmission element and a coupling link, wherein the latching hook is adapted for locking the actuatable door in a closed position. The latching hook is pivotally mounted to the associated pivot bearing and connected to the pivotable mechanical transmission element via the coupling link. The coupling link is pivotally mounted to the latching hook and to the pivotable mechanical transmission element. The pivotable mechanical transmission element is coupled to the rotatable latching shaft such that rotation of the rotatable latching shaft in operation upon actuation results in pivoting of the pivotable mechanical transmission element and pivoting of said latching hook around said associated pivot bearing. The pivotable mechanical transmission element is mounted onto the rotatable latching shaft.
Advantageously, the actuating system according to the present invention comprises latching devices with a reduced number of constituent components compared to the above described conventional actuating system, while still fulfilling all relevant requirements defined by the competent authorities, such as e.g. in EASA CS 25.783.
More specifically, according to the present invention, the rotatable latching shaft is moved respectively integrated into the rotation axis of the mechanical transmission element, which is preferably implemented by a bell crank. Thus, compared to the latching device of the conventional actuating system described above, an underlying total number of constituent components can be reduced by five, as the fifth through seventh bearings, the latch lever and the second coupling rod of the conventional actuating system are no more required. Furthermore, the mechanical transmission element, i.e. the bell crank can be simplified with respect to the bell crank known from the conventional actuating system described above, as a corresponding attachment part for attachment to the second coupling rod is no more required.
In other words, the inventive latching device has a shorter design and consists of a reduced number of constituent components including only three moving parts in row with four bearings involved, count starting with the rotatable latching shaft, adding up the individual component tolerances. One of the moving parts, i.e. the mechanical transmission element, has a simpler configuration and a reduced size. Due to these differences, the inventive latching device is lighter, requires less installation space, and is simpler and cheaper than the one known from the conventional actuating system. Consequently, the inventive actuating system as a whole is lighter, requires less installation space, and is simpler and cheaper than the conventional actuating system.
Advantageously, an associated handle part for manually actuating the actuating system according to the present invention can be implemented up to the rotatable latching shaft by means of a conventional handle part that is, e.g., described in the document DE 198 25 405 C2. Thus, an initial or initiating rotation of the rotatable latching shaft is preferably realized manually, i.e. by hand force. Furthermore, the locking device that is associated with each latching device of the actuating system according to the present invention can also be implemented by the locking device that is, e.g., described in the document DE 198 25 405 C2.
However, it should be noted that implemented locking mechanics are preferably at least similar to those described in the document DE 198 25 405 C2. This likewise applies to underlying lock and interlock solutions.